1. Technical Field
This disclosure relates generally to athletic training devices, and more specifically to apparatuses that may be suited for use in promoting development of proper throwing techniques for participants in various sports (e.g., football, baseball, etc.).
2. Description of Related Art
In various athletic endeavors, the ability of a participant to rapidly and accurately complete a throwing motion is at a premium. For example, during a pass play in the sport of American football, a quarterback must be able to quickly assess the formation of the defensive players, evade a pass rush, and successfully pass the football to a teammate (who may be closely guarded by a defender). Both accuracy and quickness of delivery are directly tied to the quarterback's throwing mechanics, and may be improved by ensuring that proper technique is practiced when throwing the football.
Exemplary representations of a proper technique for throwing a football are shown with reference to FIGS. 1A-D. These figures are adapted from an article written by Dub Maddox, coach at Jenks High School in Oklahoma. See smartfootball.com/quarterbacking/can-a-quarterbacks-throwing-motion-be-improved (posted on Aug. 22, 2011) (hereafter, Maddox Article). The Maddox Article states that “[t]hrowing the football well is not about doing one or two big things great”; instead, “it's about perfecting a thousand different parts of an intricate, complicated kinetic chain that starts in the toes and ends at the finger tips.” See Maddox Article (quoting David Fleming, “The Pursuit of Throwing Perfectly,” Apr. 21, 2010, available at sports.espn.go.com/espn/page2/story?page=fleming/100421). FIGS. 1A-D are adapted from this article and depict four arm positions within this “kinetic chain.” FIG. 1E is an additional figure that depicts the final follow-through position of throwing hand at the end of this “kinetic chain.”
Turning now to FIG. 1A, a representation of quarterback 10 is shown holding a football in a position that can be referred to as the “pre-pass triangle,” as indicated by reference numeral 12. The Maddox Article explains that this position “provides for a powerful position to launch the football”:                The kinetic chain in the arm starts in the Pre Pass Triangle position. With the elbows level at the base and a loaded wrist in the “cocked” position off the back shoulder, the triangle shape provides for a powerful position to launch the football. If the body was going to throw a punch it would load the arm instinctually in the same position. The Pre Pass Triangle position reduces tendency to internally rotate (wind up) on the throw, aligns arm in a power position, and reduces wasted motion for [ ] a faster release.This position may be referred to using different nomenclature. For example, some quarterback coaches may call this position the “ready position,” the “pyramid position,” the “throwing pocket,” or the “loaded position.” In this position, the quarterback grips the ball with both hands with elbows relaxed by the rib cage. This is a secure ball carriage position for a quarterback getting ready to throw the ball, whether the quarterback is dropping back, sprinting out, bootlegging, etc.        
Turning now to FIG. 1B, a representation of quarterback 10 in the “L position” is shown. To get to this position, the quarterback breaks the two-handed grip of football from the pre-pass triangle position 12 by taking the football in the throwing hand, and bringing the football to a position 22 that is above the quarterback's throwing shoulder. A common coaching term for the action needed to get to this position is “up and out,” meaning that the quarterback should bring the football up to a nearly fully extended arm position and away from the passer's head to this cocked position in which the arm forms an “L”. At this point, the forward throwing motion can begin. The Maddox Article elaborates on the manner in which the quarterback's rotator cuff muscles contribute to raising the arm to the L position:                The move to this position is done by using the 4 rotator cuff muscles that surround the scapula. The infrasprinatus and teres minor externally rotate the arm back into the “L” position. When the arm is in the “L” position it elongates the suprasprinatus and subscapularis which allow the muscles to accelerate the elbow to the lead position.        
Turning now to FIG. 1C, a representation of quarterback 10 with his arm in position 32 is shown. This position is also depicted by an angle marking of 45 degrees found in the Figure, which describes the desired position of the upper arm at this stage in the throwing motion. The Maddox Article describes this position as follows:                [This is t]he lead position the elbow has to be in to support the wrist. You may have heard coaches say “get the elbow up”. The elbow only needs to go high enough to get over and ahead of the shoulder on the throw. The smoothness and efficiency of this move is the key to consistent power and accuracy on a throw. With the loading of the suprasprinatus and subscapularis muscles in the “L” position the elbow can now elevate and move ahead of the shoulder aided by the deltoid to get to “Zero”. “Zero” is orthopedic term given to the elbow in the lead position because the rotator cuff muscles are neutral with no strain on them. The “Zero” position places the elbow 6 inches ahead of the shoulder 45 degrees up and out and loads the tricep in a position to fire the ball down the target hallway.Here, quarterback 10 has begun the forward motion of the football by leading with violent and forceful elbow action of the throwing arm. The football is now at its highest point in the delivery motion, and quarterback 10 has the nose of the ball pointed forward toward the intended target. As quarterback 10 continues the throwing motion from position 32, the arm action burst forward is led by the elbow.        
Turning now to FIGS. 1D and 1E, representations of quarterback 10 in follow-through positions 42 and 46 are shown. Position 42 is the beginning of the follow-through stage, and position 46 is the end of the follow-through stage. The Maddox Article describes position 42 as follows:                The kinetic chain of power that occurs as the tricep fires energy up through arm and out through the wrist/fingers into the ball. If the wrist fires early before the tricep the kinetic chain is out of order and the ball will sail or wobble. A quarterback that pulls down on the football does not extend and therefore is not getting the full benefit of the tricep. When trying to understand the power of extension on a throw, think of the difference between a pistol and a sniper rifle. Which one is more accurate and can shoot the bullet further? The sniper rifle. Why? It has a longer barrel that allows the force and spin to act longer on the bullet which in turn puts more accuracy and velocity in the bullet as it comes out of the barrel.In position 42 depicted in FIG. 1D, a downward diagonal direction begins to bring the throwing arm across the sternum area of his chest. The arm maintains full extension at the elbow as the shoulders begin to rotate counter-clockwise for a right-handed thrower and clockwise for a left-handed thrower. This shoulder rotation shows the non-throwing shoulder now moving to the posterior of torso and the throwing shoulder moving to the anterior of the torso in a twisting action. In final position 46, the throwing hand of quarterback 10 will be at the opposite hip of his torso as shown in FIG. 1E. The correct final follow-through position is achieved with a lightning-quick throwing arm action that finishes with the throwing hand at the opposite hip or belt line of quarterback 10 (as illustrated by position 46 in FIG. 1E).        